July 21, 2011
When I pack my lunch box in the morning, my thermos of tea and whatever I’ve decided to have for a midday meal is always accompanied by a banana. Force of habit—it has been my default snack-on-the-go of choice since my mom was packing lunches for me to take to school. And it’s a pretty popular fruit. The United States (as of 2005) consumes approximately 15 percent of the 80 million tons of bananas produced globally per year. But the sunshine yellow Cavendish bananas we see in the grocery store are the result of thousands of years of domestication—and a new study takes a multidisciplinary approach to figure out when and where wild bananas were tamed.
First off, a quick genealogical history: One of the fruit’s wild ancestors is the Musa acuminata, a spindly plant with small, okra-like pods that were bred to produce seedless fruit. At one point, this was crossed with the heartier-looking Musa balbisiana to create plantains, and it is from plantains that our modern varieties of bananas are derived. (And yes, there’s more than just the supermarket variety.) Banana pollen and stem imprints and other sorts of fossils do show up in the archaeological record, and it looks like Musa acuminata has been cultivated since at least 6,500 years ago; the oldest evidence comes from New Guinea. The study traced the spread of bananas around the world by looking at linguistic history, working on the premise that a cultivated plant carries its name wherever it goes, and if that plant is successful in a new culture, the plant’s name is retained. Trumping the cliché of Eskimos having 100 words for snow (or however that urban legend goes), Melanesia has more than 1,000 terms for different varieties of bananas. Combining archaeological, genealogical and linguistic studies, they trace various hybridizations and conclude that bananas were introduced to Africa at least 2,500 years ago.
But as it turns out, the Cavendish we hold so near and dear needs to do a little more evolving if it is going to hold on. On a genetic level, our supermarket bananas lack diversity, meaning they are especially susceptible to disease, such as black sigatoka, a fungal disease that is proving to be impervious to fungicides. Such pests are putting this variety of banana at risk—with some scientists saying it is careening toward extinction. Some creative cultivation may be required. A candidate for a new supermarket variety of banana is the Yangambi Km5, which is native to the Democratic Republic of Congo. A fertile plant and highly resistant to disease, the only trait keeping it from being suitable for shipping is its thin peel.
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